Smoke generating device



y 1 1952 R. STEVENSON 2,603,607

SMOKE GENERATING DEVICE Filed Feb. "7, 1944 5 lzvx/ezv-ro 7 0 Frans/W 0 I 3 2 k I 5 rrORr/EV governmental purposes, without the me of any royalty thereon.

Patented July 15, 1952 UNITED STATES.

s PATENT sales I SMOKE GENERATING DEVICE Reston Stevenson, New York, N. Y., assignor to I the United States of America as represented by the Secretary of War Application February 7, 1944, Serial No. 521,417

2 Claims. 1

. The invention described herein may bemanu- 'factured and used by or for the Government for payment to This invention relates't'o a type of device useful for forming an aerosol dispersion of'screening smokes, irritant smokes, toxic smokes and I simulated toxic smokes. It is a device which may be described as-a smoke candle or smoke pot and which is particularly well adapted for producing particulate clouds of irritant or vesicant smokes which have ability to penetrate gas mask canisters :and are difficult tdprotect against.

'An object of this invention is to provide a chemical warfare smoke agent generator, having a simp'lified construction, adapted for convenient manufacture, shipping and salvaging.

, Another Object of this invention is to provide a generating device which is capable of producing vast clouds of colloidally dispersed particles from difiicultly. vaporized substances.

. A further object of this invention is to provide I an efiicient method of forming highly dispersed I aerosols from substances which have a tendency to decompose at their normal vaporization temperatures.

Additional objects will be understood fromthe Hitherto, irritant smoke candles and; smoke pots, in general, have operated on the principle of steam distillation bypassing a stream of hot gases from a fuel over a solid block of the agent, through a series of ducts and flues formed by baillesr 'The internal constructionof these devices is somewhat complicated, making the cost of construction high and making salvaging of I these devices difficult. Parts of the solid agent are exposed in these devices to intense radiant heat and conducted heat, which tends to cause decomposition of many agents. Furthermore, the effectiveness of these devices for obtaining a highly I dispersed aerosol has been subject to improvement in ordertoobtain clouds which are more extensive, more capable of penetrating filters, and

I more persistentin suspension.

Factors influencing therate, degree and efficiency of dispersion of smoke particles into air include: the temperature atwhich the smoke agent "is vaporized; the rate of vaporization; the rate at v i: which the vapors'are cooled in coagulating; and

the rateat which air is mixed with'the coagulat- "ingsmokeparticles. There are'stil'l other factors of less determinate nature, such as the presenceof ionized gasand the ionization of thei smoke I particles. Y n

The principal features of interest for use where needed and desired in the present invention include: (a) use of granulated or loosely packed solid agent on a screen or perforated plate through which hot gas passes from a fuel chamber to intimately contact with a large free-surface area of the agent; b) the use of a device which effects rapid cooling of the vaporized agent and rapid mixing of the ooagulated smoke particles with air, preferably the use of a Venturi-type ejector, more particularly a flat ejector that forms a ribbon-like smoke stream; the use of a layer I of granulated or loosely packed solid material vention, in addition to its advantageous features for efiicient smoke generation, has the advantages I of substantially eliminating complicated internal "following disclosure and accompanyingdrawing. I

baffle structure. The generator can be readily filled, disassembled, refilled and reassembled. It can be made into a large-size stationary type for generating a lasting smoke, yet can be transported in sections for emplacement. It can also be made in a readily portable small-size type. It can be made in any desired shape, e. g" cylindrical or I box type, and convenient for shippingwith low space displacement. a

In the accompanying drawing are illustrated diagrammatically two types of smoke generators embodying features of the present invention.

' Figure 3.

' Figure 1 shows a top view of the generator.

Figure 2 shows a vertical cross-sectional view of a four-section, three-compartment generator.

Figure 3 shows a vertical cross-sectional view of a two-section, two-compartment generator.

Referring to Figure2, there is shown-a smoke generator assembly comprisinga bottom receptacle section. I for containing a block of fuel 2, such as smokeless powder. This bottom receptacle for fuel is closed at the bottom. 3 and at the sides 4, but a restricted entrance 5 is provided for introducing an igniting means,- suchv as a fuze 6, or for manipulation of .a lighting means, such as a match-head scratcher' wire 1, illustrated in u e p'psed d'i it hs the ott 'r ri rcp- '55 tacle 1 -may be one ormore intermediate body discharge end to 3 sections, such as sections 8 and 9. These'intermediate sections are open at the top and bottom and have flanged side walls. Each of these sections is attached to an adjacent section by bolts and nuts ill or equivalent clamping devices to secure the flanges together, preferably with gaskets ll between the flanges. Each of the pairs of flanges also serves to hold in place a screen, grid or perforated plate retaining means 12 and i3. These retaining means are used for supporting loosely packed or granulated solid material while being gas permeable to permit free flow of gaseous fluid into and through the supported material from a compartment underneath.

A flanged cover plate fie-attached at the flange to the upper flange of the top compartment. This cover is provided with a gas and vapor outlet opening 15, which is threaded to receive a threaded nipple I6 of an ejector device. the gas and vapor passthrough the center thereof and'are discharged through'a'restricted open.-

ing l1, thence into the Venturi tube l8 of the ejector. Upon flow into the constricted channel of tube or'co'nduit 18, the gases and vapors develop a suction whichcauses air to be drawn in at the inlet IQ of the Venturi tube. The mixture of gas vapor and air, upon flowing through the constricted passage of the Venturi tube, undergoes a substantially homogeneous intermingling; and'the mi'xture'be'comes rapidly expanded and cooled. V

As illustrated in Figure l,fthe ejector is flat and broadened so that the issuing fluid mixture comes out as a ribbon. Modification of this unit was made employing parts of a Meker burner as an exit tube. 'Howeven-the ribbon-forming type of ejector produced a much finer aerosol.

In an operation demonstrating'the'use of the generator illustrated in Figure 2, the bottom compartment I was made'to hold a fuel block composed essentially of I400 grams'ammonium nitrate-charcoal mixture of which 83.4% was ammonium nitrate. -On *theflrst'grid l2 was placed 1 kilogram of ammonium carbonate. On,

the second grid [3 was placed thex'smoke agent invarying quantities'ranging from about 1 kilogram to 2 kilograms.v The. fuel mixture was ignited through a commonpowder fuze, and a highly effective aerosol cloudwas' produced.

Ina test generator of the type illustrated in Figure 2, the four'sections were cylindrical in shape and werefltted together at'their external Two /8-inch asbestos gaskets were placed between each pair of flanges. The sections were made from cold drawn seamless steeltubing '7 inches 0. D. withq e inch-wall. The height of thebottom'section' wasfi inches. The height of'the next upper section 8 was 3% inches and of the top chamber-9 was 4 /2 inches, and the depth of the top cover was about 1 inch. The retaining screen [2 for supporting the layer of ammonium carbonate 2!! was a 12 W12 mesh 0.023 inch steel wire cloth. The retainingmeans i3 for the loosely packed smo-ke agent layer 2| was a by 20 mesh 0.016 inch steel wirecloth."

The nipple It acts as a nozzle so that The outlet opening I5 in the cover was /2:'i1lch.

The Venturi ejectortube 3% inches long and inch wide was constricted at the middle to 4 inch inside dimension'and expanded at the tube was spot brazed to the nipple l6. The nipple was made from a standard iron nipple 1 inch long. The ejector device is screwed into the cover, so that it may be readily /8 inch inside dimension. This detached for convenience,

of shipment. A 20-mesh wire cloth 22 may also be used above the layer of smoke-forming agent to prevent clogging of the outlet.

In the compartment between the fuel compartment and the smoke agent, instead of using ammonium carbonate, other substances which tend to evolve gas at temperatures of the order desired for vaporizing the smoke agent may be used. An endothermically decomposable substance in the intermediate compartment may be used to aid in preventing decomposition of a smoke agent that cannot withstand the heat of hot gases'directly from the fuel. A decomposable substance in theintermediate compartment may be selected to evolve gases of suitable ionization propertiesfor inhibiting coagulation and precipitation of the smoke agent particles. For example, salts, suchas sodium bicarbonate, ammonium chloride, ammonium sulfate or sodium sulfite, may be selected. Also, such substances in the intermediate compartment are effective for controlling the volume and velocity of gaspassed through the generator.

If desired, substances may-be mixed intimately with the intended smoke agent in order to modify its vaporization. Aside from substances which gasify for this purpose, there may be used substances which increase the'vaporppressure of the smoke agents. Substances capable of performing this function are ,SOlidS'WhiCh,'Wh6I1 mixed with the solid smoke -agent,-are'miscible therewith in the molten state. -For example-using a diphenyl or diphenylamine "as .a smoke agent, the added substance may 'be .ammonium-stearate, cyanacitic acid, or 2,4,6-tribromophenol.

In the modified apparatus'illustrated inFigure 3, there may be only two compartmentsor sections: fuel receptacle section 1 containing a fuel cake '2, and an upper smoke agent compartment 2|. The upper compartment body includes a cover or top closure 22' and is-connectedthrough threaded outlet l5'to thejejector Iil'inamanner described with respectto Figure2. The upper compartment is secured by bolted flanges to'the bottom'compartment with gaskets I land a supporting screen 23 clamped between the'fianges. The screen supports a loosely packedilayer of solid-smoke agent, whichmay be mixed witha the kinds described; or the screen maysupport a layer 20 of a decomposablesubstance, suchas ammonium carbonate, for reducing the'temperature of the heating gases and increasing the volume of the gases; and a layer2l ,of'loosely packed solid smoke agent mayrest superimposed on this layer.

The solid substance tending togasify, e. g., ammonium carbonate, may thusgbe placed-in a position to avoid thermal decompositionpf a solid smoke agent by preventing direct radiant heat of the burning fuel fromtreaching' the smoke agent. Also, the solid smoke .agen t does not have to rest as a solidblockoniahighly heated plate above the fuel, and accordingly the ,smokeagent is protected against overheatingby' .heatofconduction. The. loosely packed, smoke. agentsupported by a. screen or similar. retainen receives heat mainly and almostentirelylby convection fromgaseous products of. combustionmoderated in temperature and increased -in volume bygas evolved from the intervening layer-of the decomposable substance. It .is also. possible :to use-,2.

substance which gasifies to form anoxious gas as In Figure 3 is illustrated another form of igniting device which may be used in any. modification of the generator. This ignition device comprises a match-head 24 and a scratcher wire I havin a phosphorus coating, e. g., a coating of red phosphorus (6 parts), fine sand (3 parts) with 2 parts dextrine as binder. The match-head, e. g., a mixture of KClOs (5 parts), antimony sulfide (2 parts), and dextrine (1 part), is crimped into a zinc cup 26 set in the center on the surface of the fuel cake 2 and held in place by anchor posts 21 that pierce the cup and are imbedded in the cake. The tops of the anchor posts have loops 28 which serve as guides for the scratcher wire I. The coated portion of the wire normally lies to one side of the match-head. The uncoated portion of the wire extends outward through a hole 5 in the side of the compartment where it terminates in a ring or band for manipulation. The ring or band is held in place against the exterior side wall by a tape until used. When the generator is to be fired, it is placed on the ground in an upright position with the ejector attached and with the tape removed, and the wire is pulled outward quickly to make the seratcher rub against and set afire the match-head.

Still other types of ignition devices may be used with the generators, such as those having a striker, primer and starter, as in smoke candles.

With its simplified internal arrangement, the present generator is adapted to be made in a form which readily and automatically rolls into an upright position regardless of the position in which it falls or is placed upon the ground. To have this form, the smoke generator may be provided with a weighted bottom and a rounded body shape. The top and bottom parts of the generator body need not be held together by bolted external flanges; they may be secured together by a friction fit, by threading, a slot and bead combination or similar means which leave the body exterior smooth and avoid interference with the pot righting itself. The ejector or means for emitting the smoke from the generator may be placed at the top of the generator. An advantage of this type of smoke pot is that such pots can be dropped from fast-moving armored cars or tanks or even dropped with parachutes from airplanes, and when thus distributed with adequate security in a field of combat, will operate efiiciently by assuming an upright position automatically.

The generator of this invention is capable of making a highly effective dispersion of noxious gases and irritant smokes from solid agents which are difiicult to vaporize or disperse normally Without decomposition, such as diphenylaminechlorarsine, diphenylcyanarsine and the like. It further makes an improvement in the dispersion of agents which could not be efiectively dispersed by other means, for example, solid toxic vesicants, such as mustard sulfone. j

The generators may have a thermal insulatin material covering for increasing their heat efiiciency and to give them protection in shipment.

When the generators, are not in use and the smoke ejector-attachment is not in place, the smoke outlet opening It": may also be stoppered or taped as well as the ignition device opening.

In addition to the many technical advantages, the smoke generator of this invention very well satisfies tactical requirements in its simplicity, a large-mass cloud formation capacity, flexibility and adaptability for movement and emplacement.

Principles of the invention have industrial apaerosols by sublimation into fine particles from various solid substances, and particularly in treating substances which are difiicult to vaporize without thermal decomposition.

It is to be understood that although the invention has been described with reference to specific illustrations of its embodiment, other modifications come within the spirit and scope thereof.

I claim:

1. A device for generating a smoke having noxious physiological efiects from a solid material having a tendency to decompose when vaporized in the device at an elevated temperature; said device being tubular in vertical cross section and including an upper chamber portion and a lower chamber portion adapted to be readily connected together in a substantially airtight manner and when so connected are separated from each other by a gas pervious diaphragm adapted to prevent the passage of large particles of solid material between said chamber portions, said upper portion being provided with a fiat, broad Venturi type projector consisting of a nozzle member operatively secured and in communication with said upper chamber portion and having on its outer end portion a tubular member open at either of its end portions to the outer atmosphere and having its upper and lower wall portions arcuate in form and converging at their midsections in a manner adapted to mix atmospheric air with the smoke projected from said nozzle between said upper and lower wall portions and to project the intermingled air and smoke into said air in a ribbon-like stream.

2. A device for generating a smoke having noxious physiological efiects from a solid material having a tendency to decompose when vaporized in the device at an elevated temperature; said device being tubular in vertical cross section and including an upper chamber portion, an intermediate chamber portion and a lower chamber portion adapted to be readily connected together in a substantially airtight manner and when so connected are separated from each other by a gas pervious diaphragm adapted to prevent the passage of large particles of solid material between said chamber portions, said upper portion being provided with a flat, broad Venturi type projector consisting of a nozzle member operatively secured and in communication with said upper chamber portion and having on its outer end portion a tubular member open at either of its end portions to the outer atmosphere and having its upper and lower wall portions arcuate in. form and converging at their midsections in a manner adapted to mix atmospheric air with the smoke projected from said nozzle between said upper and lower wall portions and to project the intermingled air and smoke into said air in a ribbon-like stream.

RESTON STEVENSON.

. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 16,841 Bradner Jan. 3, 1928 1,336,557 Benner et a1 Apr. 13, 1920 2,105,522 Clevenger Jan. 18, 1938 

1. A DEVICE GENERATING A SMOKE HAVING NOXIOUS PHYSIOLOGICAL EFFECTS FROM A SOLID MATERIAL HAVING A TENDENCY TO DECOMPOSE WHEN VAPORIZED IN THE DEVICE AT AN ELEVATED TEMPERATURE; SAID DEVICE BEING TUBULAR IN VERTICAL CROSS SECTION AND INCLUDING AN UPPPER CHAMBER PORTION AND A LOWER CHAMBER PORTION ADAPTED TO BE READILY CONNECTED TOGETHER IN A SUBSTANTIALLY AIRTIGHT MANNER AND WHEN SO CONNECTED ARE SEPARTED FROM EACH OTHER BY A GAS PERVIOUS DIAPHRAGM ADAPTED TO PREVENT THE PASSAGE OF LARGE PARTICLES OF SOLID MATERIAL BETWEEN SAID CHAMBER PORTIONS, SAID UPPER PORTION BEING PROVIDED WITH A FLAT, BROAD VENTURI TYPE PROJECTOR CONSISTING OF A NOZZLE MEMBER OPERATIVELY SECURED AND IN COMMUNICATION WITH SAID UPPER CHAMBER PORTION AND HAVING ON ITS OUTER END PORTION A TUBULAR MEMBER OPEN AT EITHER OF ITS END PORTIONS TO THE OUTER ATMPSPHERE AND HAVING ITS UPPER AND LOWER WALL PORTIONS ARCUATE IN FORM AND CONVERGING AT THEIR MIDSECTIONS IN A MANNER ADAPTED TO MIX ATMOSPHERIC AIR WITH THE SMOKE PROJECTED FROM SAID NOZZLE BETWEEN SAID UPPER AND LOWER WALL PORTIONS AND TO PROJECT THE INTERMINGLED AIR AND SMOKE INTO SAID AIR IN A RIBBON-LIKE STREAM. 